1. Field of the Invention
The invention relates to a belt braking system for safety belts in motor vehicles and, more particularly, refers to a new and improved belt band-clamping arrangement in combination with an automatic roll-up device in which the belt can be reeled up on a belt drum and reeled off against a spring load.
2. Description of the Prior Art
A known deflector fitting with clamping arrangement for a safety belt, German Published Non-Prosecuted Application No. 2,540,302, has a double-armed lever deflector element which can be swiveled and is supported on a U-fitting plate. The element is equipped on one lever arm with a round deflector pin having a rounded deflector surface while the other lever is developed as part of the clamping device. The belt is wrapped around the top deflector peg and is run between a clamping surface of the bottom lever arm and a clamping surface mounted on the fitting plate. The deflector element with respect to the clamping device is kept at a released position by a spring load on one of the lever arms. With the occurrence of a suddenly increased load on the belt band, the double-armed lever is deflected by a torque produced on the lever-like deflector element, which locks and brakes the belt band between deflector element- and fitting plate clamping surfaces. With a slackened load the deflector element is automatically swiveled back to its released position by the force of the spring. The fabrication of a deflector element in accordance with the design of this concept is expensive since it requires an extremely stable deflector element and support because on being subjected to loadings, extremely high lever forces--produced by the relatively large-size lever arms--act on the deflector element and the swiveling support.
A roll-up device for a safety belt is disclosed in German Published Prosecuted Application No. 1,481,969, in which a fitting housing encloses a belt drum provided for belt storage, and a clamping device for belt clamping. The clamping device includes a clamping jaw having a circular segmental shape is supported to swivel at its center on the housing. The belt band passes around the circular segmental shape of the clamping jaw. A further stationary clamping jaw is arranged at the housing at the belt surface level. In operational connection with the clamping jaw which swivels is a spring loaded braking device following a belt reel-off and brief belt band rereeling--e.g. in case of a crash--both of said clamping jaws are clamped together, and the braking device locks the swivelable clamping jaw and prevents any further reel-off. The braking device has a mechanism which keeps the clamping jaw which swivels at a released position. This mechanism can be manually timed at various actuating positions, e.g. in a release for putting on the safety belt. This mechanism, too, is expensive and difficult to operate.